Is binge-watching addictive? Effects of motives for TV series use on the relationship between excessive media consumption and problematic viewing habits.

This study investigates the circumstances under which binge-watching can become a problematic behavior. Applying a user-centered perspective, it demonstrates how different motivations to engage in high-dosage TV series consumption influence the occurrence of problematic viewing habits. A quantitative online survey of N = 415 media users with access to at least one streaming service was conducted. The questionnaire assessed current viewing habits, motivations to watch series, and indicators of problematic viewing habits. The results suggest that frequency of use, motives to engage in high dosage viewing sessions, as well as the combined effect of these two factors help to explain problematic viewing behaviors. Moreover, the results give cause to refrain from a generalizing problematization of binge-watching.

The biomechanical strength of a hardware-free femoral press-fit method for ACL bone-tendon-bone graft fixation.

PURPOSE: The purpose was to investigate graft slippage and ultimate load to failure of a femoral press-fit fixation technique for anterior cruciate ligament (ACL) reconstruction. METHODS: Nine fresh-frozen knees were used. Standardized harvesting of the B-PT-B graft was performed. The femora were cemented into steel rods, and a tunnel was drilled outside-in into the native ACL footprint and expanded using a manual mill bit. The femoral bone block was fixed press-fit. To pull the free end of the graft, it was fixed to a mechanical testing machine using a deep-freezing technique. A motion capture system was used to assess three-dimensional micro-motion. After preconditioning of the graft, 1000 cycles of tensile loading were applied. Finally, an ultimate load to failure test was performed. Graft slippage in mm ultimate load to failure as well as type of failure was noted. RESULTS: In six of the nine measured specimens, a typical pattern of graft slippage was observed during cyclic loading. For technical reasons, the results of three knees had to be discarded. 78.6 % of total graft slippage occurred in the first 100 cycles. Once the block had settled, graft slippage converged to zero, highlighting the importance of initial preconditioning of the graft in the clinical setting. Graft slippage after 1000 cycles varied around 3.4 ± 3.2 mm (R = 1.3-9.8 mm) between the specimens. Ultimate loading (n = 9) revealed two characteristic patterns of failure. In four knees, the tendon ruptured, while in five knees the bone block was pulled out of the femoral tunnel. The median ultimate load to failure was 852 N (R = 448-1349 N). CONCLUSION: The implant-free femoral press-fit fixation provided adequate primary stability with ultimate load to failure pull forces at least equal to published results for interference screws; hence, its clinical application is shown to be safe.

[Areas of application of isothermal microcalorimetry in urology: an overview]. / Anwendungsbereiche der isothermalen Mikrokalorimetrie in der Urologie : Eine Übersicht.

Isothermal microcalorimetry (IMC) is a nonspecific analytical tool for measurement of heat. With sensitivity in the order of 0.2 µW, IMC can detect very small amounts of heat produced by only a small number of microorganisms or eukaryotic cells. This report is intended to introduce IMC to the urological audience and to give an overview about the past, present and future of this cutting edge technology in the urological context.

Double-network acrylamide hydrogel compositions adapted to achieve cartilage-like dynamic stiffness.

Since articular cartilage has a limited potential for spontaneous healing, various techniques are employed to repair cartilage lesions. Acrylate-based double-network (DN) hydrogels containing ~90% water have shown promising properties as repair materials for skeletal system soft tissues. Although their mechanical properties approach those of native cartilage, the critical factor-stiffness-of DN-gels does not equal the stiffness of articular cartilage. This study investigated whether revised PAMPS/PAAm compositions with lower water content result in stiffness parameters closer to cartilage. DN-gels containing 61, 86 and 90% water were evaluated using two non-destructive, mm-scale indentation test modes: fast-impact (FI) and slow-sinusoidal (SS) deformation. Deformation resistance (dynamic modulus) and energy handling (loss angle) were determined. The dynamic modulus increased with decreasing water content in both testing modes. In the 61% water DN-gel, the modulus resembled that of cartilage (FI-mode: DN-gel = 12, cartilage = 17; SS-mode: DN-gel = 4, cartilage = 1.7 MPa). Loss angle increased with decreasing water content in fast-impact, but not in slow-sinusoidal deformation. However, loss angle was still much lower than cartilage (FI: DN-gel = 5, cartilage = 11; SS: DN-gel = 10, cartilage = 32°), indicating somewhat less ability to dissipate energy. Overall, results show that it is possible to adapt DN-gel composition to produce dynamic stiffness properties close to normal articular cartilage.

Application of a microcalorimetric method for determining drug susceptibility in mycobacterium species.

Mycobacterium tuberculosis is a global public health concern, particularly with the emergence of drug-resistant strains. Immediate identification of drug-resistant strains is crucial to administering appropriate treatment before the bacteria are allowed to spread. However, developing countries, which are most affected by drug resistance, are struggling to combat the disease without the facilities or funds for expensive diagnostics. Recent studies have emphasized the suitability of isothermal microcalorimetry (IMC) for the rapid detection of mycobacteria. In this study, we investigate its suitability for rapid and reliable M. tuberculosis drug susceptibility testing. Specifically, IMC was used to determine the MICs of three drugs, namely, isoniazid, ethambutol, and moxifloxacin, against three mycobacteria, namely, Mycobacterium smegmatis, Mycobacterium avium, and Mycobacterium tuberculosis. The Richards growth model was used to calculate growth parameters, namely, the maximum bacterial growth rate and the lag phase duration from integrated heat flow-versus-time results. For example, MICs of isoniazid, ethambutol, and moxifloxacin were determined to be 1.00, 8.00, and 0.25 µg/ml, respectively. IMC, as described here, could be used not just in industrialized countries but also in developing countries because inexpensive and sensitive microcalorimeters are now available.

A comparison of healthy human and swine articular cartilage dynamic indentation mechanics.

Articular cartilage is a multicomponent, poroviscoelastic tissue with nonlinear mechanical properties vital to its function. A consequent goal of repair or replacement of injured cartilage is to achieve mechanical properties in the repair tissue similar to healthy native cartilage. Since fresh healthy human articular cartilage (HC) is not readily available, we tested whether swine cartilage (SC) could serve as a suitable substitute for mechanical comparisons. To a first approximation, cartilage tissue and surgical substitutes can be evaluated mechanically as viscoelastic materials. Stiffness measurements (dynamic modulus, loss angle) are vital to function and are also a non-destructive means of evaluation. Since viscoelastic material stiffness is strongly strain rate dependent, stiffness was tested under different loading conditions related to function. Stiffness of healthy HC and SC specimens was determined and compared using two non-destructive, mm-scale indentation test modes: fast impact and slow sinusoidal deformation. Deformation resistance (dynamic modulus) and energy handling (loss angle) were determined. For equivalent anatomic locations, there was no difference in dynamic modulus. However, the HC loss angle was ~35% lower in fast impact and ~12% higher in slow sinusoidal mode. Differences seem attributable to age (young SC, older HC) but also to species anatomy and biology. Test mode-related differences in human-swine loss angle support use of multiple function-related test modes. Keeping loss angle differences in mind, swine specimens could serve as a standard of comparison for mechanical evaluation of e.g. engineered cartilage or synthetic repair materials.

Evaluation of a low-cost calorimetric approach for rapid detection of tuberculosis and other mycobacteria in culture.

AIMS: The objective of this study was to evaluate the effectiveness of microcalorimetry in rapid detection of mycobacterium species using an inexpensive Isothermal microcalorimetry (IMC) instrument. In addition, we compared microcalorimetry with conventional monitoring techniques. METHODS AND RESULTS: Isothermal microcalorimetry measures heat production rate and can provide rapid detection of living mycobacteria in clinical specimens. Using liquid medium showed that bacterial activity measured by IMC using a TAM Air® agreed with the triphenyl tetrazolium chloride (TTC) assay. Using solid medium to enhance growth, fast-growing mycobacteria detection was achieved between 26 and 53 h and slow-growing mycobacteria detection was achieved between 54 and 298 h. In addition, the calorimetric data were analysed to estimate the growth rate and generation time of the mycobacteria monitored. SIGNIFICANCE AND IMPACT OF THE STUDY: Infections caused by mycobacteria are severe and difficult to treat. With 9·27 million new cases of tuberculosis in 2007, developing countries experience severe health and economic consequences owing to the lack of an affordable, fast detection method. Research-grade IMC instruments are too expensive to use in developing countries. Our study demonstrates that less-expensive instruments such as the TAM air® are adequate for mycobacteria detection and therefore establishes a clear proof of concept.

Real-time measurements of human chondrocyte heat production during in vitro proliferation.

Isothermal microcalorimeters (IMC) are highly sensitive instruments that allow the measurement of heat flow in the microwatt range. Due to their detection of minute thermal heat, IMC techniques have been used in numerous biological applications, including the study of fermentation processes, pharmaceutical development, and cell metabolism. In this work, with the ultimate goal of establishing a rapid and real-time method to predict the proliferative capacity of human articular chondrocytes (HAC), we explored to use of IMC to characterize one of the crucial steps within the process of cartilage tissue engineering, namely the in vitro expansion of HAC. We first established an IMC-based model for the real-time monitoring of heat flow generated by HAC during proliferation. Profiles of the heat and heat flow curves obtained were consistent with those previously shown for other cell types. The average heat flow per HAC was determined to be 22.0 ± 5.3 pW. We next demonstrated that HAC proliferation within the IMC-based model was similar to proliferation under standard culture conditions, verifying its relevance for simulating the typical cell culture application. HAC growth and HAC heat over time appeared correlated for cells derived from particular donors. However, based on the results from 12 independent donors, no predictive correlation could be established between the growth rate and the heat increase rate of HAC. This was likely due to variability in the biological function of HAC derived from different donors, combined with the complexity of tightly couple metabolic processes beyond proliferation. In conclusion, IMC appears to be a promising technique to characterize cell proliferation. However, studies with more reproducible cell sources (e.g., cell lines) could be used before adding the complexity associated with primary human cells.

Kinematical and EMG-classifications of a fencing attack.

8 expert fencers were studied with a 3-dimensional motion analysis system. Each subject performed 10 flèche attacks toward a standardized target. Surface electromyography signals (EMG) were recorded of the deltoid pars clavicularis, infraspinatus and triceps brachii caput laterale muscles of the weapon arm. The recorded EMGs were averaged using EMG wavelet-transformation software. 4 phases were defined based on the arm kinematics and used to classify fencers into 2 groups. A first group of 4 fencers showed an early maximal elbow extension (Early MEE) whereas the second group presented a late maximal elbow extension (Late MEE). 2 EMG-classifications were based on this kinematical classification, one in the time-domain and the other in the frequency-domain by using the spherical classification. The time-domain EMG-classification showed a significantly ( P=0.03) higher normalized deltoid intensity for the Early MEE group (91 ± 18%) than the Late MEE group (36 ± 13%) in the attack phase. The spherical classification revealed that the activity of all the muscles was significantly classified (recognition rate 75%, P=0.04) between the 2 groups. This study of EMG and kinematics of the weapon upper limb in fencing proposes several classifications, which implies a relationship between kinematic strategies, muscular activations and fencing success.

Are ankle chondrocytes from damaged fragments a suitable cell source for cartilage repair?

OBJECTIVE: To characterize the post-expansion cartilage-forming capacity of chondrocytes harvested from detached fragments of osteochondral lesions (OCLs) of ankle joints (Damaged Ankle Cartilage Fragments, DACF), with normal ankle cartilage (NAC) as control. DESIGN: DACF were obtained from six patients (mean age: 35 years) with symptomatic OCLs of the talus, while NAC were from 10 autopsies (mean age: 55 years). Isolated chondrocytes were expanded for two passages and then cultured in pellets for 14 days or onto HYAFF-11 meshes (FAB, Italy) for up to 28 days. Resulting tissues were assessed histologically, biochemically [glycosaminoglycan (GAG), DNA and type II collagen (CII)] and biomechanically. RESULTS: As compared to NAC, DACF contained significantly lower amounts of DNA (3.0-fold), GAG (5.3-fold) and CII (1.5-fold) and higher amounts of type I collagen (6.2-fold). Following 14 days of culture in pellets, DACF-chondrocytes generated tissues less intensely stained for Safranin-O and CII, with significantly lower GAG contents (2.8-fold). After 28 days of culture onto HYAFF((R))-11, tissues generated by DACF-chondrocytes were less intensely stained for Safranin-O and CII, contained significantly lower amounts of GAG (1.9-fold) and CII (1.4-fold) and had lower equilibrium (1.7-fold) and dynamic pulsatile modulus (3.3-fold) than NAC-chondrocytes. CONCLUSION: We demonstrated that DACF-chondrocytes have inferior cartilage-forming capacity as compared to NAC-chondrocytes, possibly resulting from environmental changes associated with trauma/disease. The study opens some reservations on the use of DACF-derived cells for the repair of ankle cartilage defects, especially in the context of tissue engineering-based approaches.

"The heat is on": rapid microcalorimetric detection of mycobacteria in culture.

Detection of mycobacterial infection can be achieved by different means; however, culture-based methods remain the gold standard. In this paper, we present a new culture-based method using real-time microcalorimetric detection of growth of Mycobacterium species including Mycobacterium tuberculosis. Microcalorimetric detection of heat production by 6 different growing species of Mycobacterium was achieved between 20 and 310h depending on their type (fast vs. slow-growing mycobacteria) and initial concentration. This study demonstrates that microcalorimetric detection of mycobacterial growth is a potential advantageous alternative to methods using fluorescent or radiolabeled growth indicators.

A comparison between ((3)H)-thymidine incorporation and isothermal microcalorimetry for the assessment of antigen-induced lymphocyte proliferation.

Lymphocyte transformation tests (LTT) are time-consuming radioactive assays used in the clinic for the determination of allergic drug reactions and extensively in basic immunological research. In the present study we propose an alternative method in the monitoring of T-cell responses by isothermal microcalorimetric (IMC) measurements of overall cellular heat production as a function of time. For mitogen-induced lymphocyte proliferation, we analyzed a concentration dependent effect of phytohemaglutinin (PHA) and both tests showed a good correlation. This was also the case for specific antigenic stimulation with Varidase(R) or tetanus toxoid. On the other hand, antigen-induced lymphocyte proliferation analyzed by pre and post influenza vaccine (Inflexal(R) V) samples, showed no such correlation. Our study suggests that IMC measurements, despite the advantages of simplicity, on-line recording of metabolic activity and no use of radioactivity, may be limited to monitoring mitogen-induced lymphocyte proliferation.

Intra-individual comparison of human ankle and knee chondrocytes in vitro: relevance for talar cartilage repair.

OBJECTIVE: As compared to knee chondrocytes (KC), talar chondrocytes (TC) have superior synthetic activity and increased resistance to catabolic stimuli. We investigated whether these properties are maintained after TC are isolated and expanded in vitro. METHODS: Human TC and KC from 10 cadavers were expanded in monolayer and then cultured in pellets for 3 and 14 days or in hyaluronan meshes (Hyaff-11) for 14 and 28 days. Resulting tissues were assessed biochemically, histologically, biomechanically and by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The proteoglycan and collagen synthesis rates in the pellets were also measured following exposure to Interleukin-1 beta (IL-1 beta). RESULTS: After 14 days of pellet culture, TC and KC expressed similar levels of type I collagen (CI) and type II collagen (CII) mRNA and the resulting tissues contained comparable amounts of glycosaminoglycans (GAG) and displayed similar staining intensities for CII. Also proteoglycan and collagen synthesis were similar in TC and KC pellets, and dropped to a comparable extent in response to IL-1 beta. Following 14 days of culture in Hyaff-11, TC and KC generated tissues with similar amounts of GAG and CI and CII. After 28 days, KC deposited significantly larger fractions of GAG and CII than TC, although the trend was not reflected in the measured biomechanical properties. CONCLUSION: After isolation from their original matrices and culture expansion, TC and KC displayed similar biosynthetic activities, even in the presence of catabolic stimuli. These in vitro data suggest a possible equivalence of TC and KC as autologous cell sources for the repair of talar cartilage lesions.

Engineered cartilage generated by nasal chondrocytes is responsive to physical forces resembling joint loading.

OBJECTIVE: To determine whether engineered cartilage generated by nasal chondrocytes (ECN) is responsive to different regimens of loading associated with joint kinematics and previously shown to be stimulatory of engineered cartilage generated by articular chondrocytes (ECA). METHODS: Human nasal and articular chondrocytes, harvested from 5 individuals, were expanded and cultured for 2 weeks into porous polymeric scaffolds. The resulting ECN and ECA were then maintained under static conditions or exposed to the following loading regimens: regimen 1, single application of cyclic deformation for 30 minutes; regimen 2, intermittent application of cyclic deformation for a total of 10 days, followed by static culture for 2 weeks; regimen 3, application of surface motion for a total of 10 days. RESULTS: Prior to loading, ECN constructs contained significantly higher amounts of glycosaminoglycan (GAG) and type II collagen compared with ECA constructs. ECN responded to regimen 1 by increasing collagen and proteoglycan synthesis, to regimen 2 by increasing the accumulation of GAG and type II collagen as well as the dynamic modulus, and to regimen 3 by increasing the expression of superficial zone protein, at the messenger RNA level and the protein level, as well as the release of hyaluronan. ECA constructs were overall less responsive to all loading regimens, likely due to the lower extracellular matrix content. CONCLUSION: Human ECN is responsive to physical forces resembling joint loading and can up-regulate molecules typically involved in joint lubrication. These findings should prompt future in vivo studies exploring the possibility of using nasal chondrocytes as a cell source for articular cartilage repair.

Cartilage tissue engineering by expanded goat articular chondrocytes.

In this study we investigated whether expanded goat chondrocytes have the capacity to generate cartilaginous tissues with biochemical and biomechanical properties improving with time in culture. Goat chondrocytes were expanded in monolayer with or without combinations of FGF-2, TGF-beta1, and PDGFbb, and the postexpansion chondrogenic capacity assessed in pellet cultures. Expanded chondrocytes were also cultured for up to 6 weeks in HYAFF-M nonwoven meshes or Polyactive foams, and the resulting cartilaginous tissues were assessed histologically, biochemically, and biomechanically. Supplementation of the expansion medium with FGF-2 increased the proliferation rate of goat chondrocytes and enhanced their postexpansion chondrogenic capacity. FGF-2-expanded chondrocytes seeded in HYAFF-M or Polyactive scaffolds formed cartilaginous tissues with wet weight, glycosaminoglycan, and collagen content, increasing from 2 days to 6 weeks culture (up to respectively 2-, 8-, and 41-fold). Equilibrium and dynamic stiffness measured in HYAFF M-based constructs also increased with time, up to, respectively, 1.3- and 16-fold. This study demonstrates the feasibility to engineer goat cartilaginous tissues at different stages of development by varying culture time, and thus opens the possibility to test the effect of maturation stage of engineered cartilage on the outcome of cartilage repair in orthotopic goat models.

Pulsatile dynamic stiffness of cartilage-like materials and use of agarose gels to validate mechanical methods and models.

Stiffness is a fundamental indicator of the functional state of articular cartilage. Reported test modes include compressive incremental strain to determine the equilibrium modulus, and sinusoidal strain to determine the dynamic modulus and stress/strain loss angle. Here, initial development is described for a method recognizing that gait is pulsatile. Agarose gels have been used by others for validation or comparison of mechanical test methods and models for cartilage and proteoglycan aggregate. Accordingly, gels ranging from 0.5 to 20% agarose were prepared. Pulsatile stiffness in both indentation and unconfined compression were closely reproducible. Stiffness as a function of agarose concentration rose exponentially, as found using other methods. Indentation stiffness was higher than for unconfined compression and ranged from approximately 2.0 kPa for 0.5% gel to approximately 3,800 kPa for 20% gel. Pulsatile dynamic stiffness appears to be a useful method, although further development is needed. Agarose gel stiffness values obtained by other methods were reviewed for comparison. Unfortunately, reported values for a given agarose concentration ranged widely (e.g. fourfold) even when test methods were similar. Causes appear to include differences in molecular weight and gel preparation time-temperature regimens. Also, agarose is hygroscopic, leading to unintended variations in gel composition. Agarose gels are problematic materials for validation or comparison of cartilage mechanical test methods and models.

[Analysis of wavelet transformed electromyographic signals that were altered by wearing a knee brace]. / Analyse der Veränderungen von Wavelet-transformierten elektromyographischen Signalen, wie sie beim Tragen einer Kniebandage entstehen.

The comparison of electromyograms represents a challenge for data analysis. The aim of the project was to present a method that uses a minimal computational effort to resolve small but significant changes in the muscular activity that occur while walking with and without a knee brace. The wavelet transformed electromyograms were represented as intensity patterns that resolve the power of the signal in time and frequency. The intensity pattern of each electromyogram defines single points in a pattern space. The distance between these points in pattern space were used to detect and show the separation between the groups of electromyograms that were recorded while walking with and without a knee brace. The method proposes a distance versus angle representation to visually discriminate the intensity patterns. Once it has been shown that the differences are statistically significant, one can visualize the result in a difference intensity pattern that indicates at what time and at what frequency the electromyograms vary between the two conditions tested. It is to be expected that interventions that are more intrusive than a knee brace will reveal even more distinct differences.

[Validation of the Tekscan system for statistic and dynamic pressure measurements of the human femorotibial joint]. / Die Validierung des Tekscan-Systems für statische und dynamische Druckmessungen am humanen Femorotibialgelenk.

In vitro dynamic pressure measurements in the healthy and pathologically altered knee joint help to improve our understanding of the loading pattern on femorotibial surfaces. The aim of the study was to evaluate a piezoresistive pressure measuring system. A human cadaveric knee was mounted in a material-testing machine (Bionix 858) using a specially designed knee-holding device. Axial loading of the knee, flexed at 20o, at 500 N, 1000N and 1500 N was then carried out. For the static investigations, the piezoresistive measuring system (Tekscan), was compared with the FUJI measuring system. In addition, dynamic measurements were also performed with the Tekscan System. With the exception of the lateral compartment at a load of 1500 N, no differences in maximum pressures were observed between the two systems. Nor were there any differences with regard to contact surfaces, either in the medial or lateral compartment (p > 0.05). However, the reproducibility of the data was significantly higher with the Tekscan System (p < 0.01). Dynamic pressure measurements obtained with the knee flexed 20 to 90o showed that the lateral contact area shifted from anterior to posterior, while the medial contact area remained virtually unchanged. The Tekscan System proved to be more reliable than the FUJI System, and permits simultaneous measurements in both compartments. The Tekscan System is suitable for dynamic measurement of the femorotibial joint, and permits measurements to be made under more physiological conditions.

Current state of cement fixation in THR.

The author surveys important landmarks in the development of total hip arthroplasty, with an accent on implant fixation using acrylic cement. He explains why he personally opted for hybrid prostheses, combining a cemented stem and a cementless socket, in patients over sixty years. Excellent cementless, sockets have been available for a long time; on the femoral side, the first steps were difficult, but several cementless, stems were subsequently developed, which provided excellent long term results. This historical evolution resulted in a very uneven use of cemented versus cementless stems from one country to another in Europe. Cemented implants have enjoyed a renewed popularity over the past few years as a result of several factors, including economical factors. The author discusses the conditions for optimal fixation of a cemented stem; these conditions are not always met satisfactorily, as a number of surgeons obviously stick to a crude cementing technique. The author describes the role of the stem geometry and surface finish, as well as the possible influence of a centralizer; he explains why, based on a correct analysis of the available data, discredit has been unduly cast on cemented stems made of titanium alloy. He insists on one important although often disregarded factor: the specific type of cement used, as better results have clearly been achieved with certain cements than with others. He insists on the necessity to take into account all the elements involved, in order to avoid making erroneous conclusions. He also insists on one very important variable, the quality of the surgical technique. Total hip arthroplasty is likely to make further progress in the future, although we are likely now in the asymptotic portion of an ascending curve. Further improvement in clinical results will result from improvement of currently existing systems and optimization of surgical technique, rather than from the continuous designing of new implants.

The patella in total knee replacement: does it matter? 750 LCS total knee replacements without resurfacing of the patella.

Hingelike moving total knee replacement (TKR) has shown that the "rotating" function of the quadriceps muscle becomes lost. Dynamic work of the vastus medialis is no longer needed, and the static part of the quadriceps muscle assumes the major part of the work, beginning with continuously dislocating the patella to the lateral side. We operated on 436 knees using the LCS (De Puy Orthopaedics, Warsaw, IN) meniscal bearing TKR. No primary patellar resurfacing was necessary in this series. The New Jersey Score increased constantly over the 5-year follow-up from 83 after 2 years to 90 after 5 years. This shows that there is no deterioration which can be attributed to a deterioration in the patellar behavior. Nonresurfacing of the patella is a possible solution if the kinematics of the TKR allow physiological rotation, the prosthesis is built anatomically, the alignment is correct, the anatomy of decelerator/extensor mechanism is respected by the approach, and ligamentous stability is good.